Load handling platform provided with retractable rollers

ABSTRACT

The invention concerns a roller track device based on simple kinematics, enabling reduction of the number of parts and production costs of the assembly as well as its space requirement, and designed for being fitted on new handling apparatuses as well as for retrofitting. The invention also concerns a platform or fork handling apparatus equipped with such a device. The roller track device ( 10 ) comprises a substantially horizontal table ( 21 ) whereon are mounted ball sockets ( 23 ), with a rack ( 31 ) mounted on top provided with openings ( 32 ) arranged opposite the balls ( 23 ). The rack ( 31 ) is mobile relative to the table ( 21 ) between a high position wherein it conceals the balls ( 23 ). A handle ( 41 ) coupled to the rack ( 31 ) enable its displacement in horizontal translation (Th). The openings ( 32 ) provided in the rack ( 31 ) consist of elliptical slots, which in combination with the spherical profiles of the underlying roller track device in the form of a platform with balls is also applicable to caster track platforms. The invention is useful for transferring heavy loads in a substantially horizontal plane with a platform handling apparatus for machine-tools, presses, injection machines and the like.

This application is a national stage completion of PCT/FR2003/003126filed Oct. 21, 2003 which claims priority from French Application SerialNo. 02/13075 filed Oct. 21, 2002.

FIELD OF THE INVENTION

The present invention concerns a roller device for moving a load in anessentially horizontal plane and a handling apparatus equipped with sucha roller device.

In industry, load handling platforms such as elevator cars and stackingequipment, for example, are currently used to handle heavy loads. Theseheavy loads might consist of tools for machine tools or presses used tocut or stamp metal, or molds or forms used in the injection of syntheticmaterial, etc. Generally, loads of less than two tons are transported onload handling platforms, while loads from two to ten tons aretransported using fork apparatuses. Loads of over ten tons aretransported by cranes.

To facilitate the transfer of loads in the horizontal plane from thehandling platform to the machine tool or vice versa, handling equipmentnow in use is provided with a roller device integral with the forks,designed to support the load and displace it without friction on thefree roller devices. This handling equipment may also be provided witharticulated arms designed to push or pull the load. The roller devicegenerally comprises a “roller support structure” surmounted by a “loadsupport structure.” The function of the load support structure is tosupport the load while the handling apparatus moves, whereas thefunction of the roller support structure is to support it withoutfriction in order to effect the transfer. Passing the load from onestructure to the other and vice versa is accomplished through thedisplacement of one structure relative to the other so that the rollerdevices on the roller-support structure can be retracted or extendedrelative to the load support structure, said relative displacement beingcontrolled by means of manual or automatic actuators.

In fork type handling apparatuses, this relative movement is generallycontrolled manually using a handle or a lever to activate rotation ofthe specific mechanisms such as, for example, cams or bearing systems.

BACKGROUND OF THE INVENTION

The mechanisms currently used in roller devices to ensure passage of theload from the “load support structure” to the “roller support structure”and vice versa present numerous drawbacks linked to their complexity,price, and space requirements. Moreover, certain mechanisms require abroad amplitude of movement, increasing the time required fortransferring the load. Moreover, these mechanisms are not adapted foruse with load handling devices already in service.

SUMMARY OF THE INVENTION

The present invention proposes remedying these disadvantages with aroller device based on simple kinematics, reducing the number of pieces,the cost of the unit, and its size, which can be used either with newload handling devices or to retrofit existing ones.

To achieve this, the invention concerns a roller device of the typeindicated in the preamble, characterized in that it comprises at leastone essentially horizontal table to which the roller elements areattached, at least one rack covering said table which has openingslocated opposite the roller devices, said rack defining a plane contactsurface capable of carrying said load when it is static and said rollermeans being located in a plane that is essentially parallel to saidsurface and capable of carrying said load when it is moving, actuatingmeans connected to at least one of these structures so as to make itmovable relative to the other between at least a lowered position and araised position, wherein the load is supported either by the rack or bythe table, in that said actuating means are designed to displace thestructure called the movable structure at least in horizontaltranslation and in that said rack comprises lifting means designed tocooperate with said roller elements on said table so as to causevertical displacement of the structure called the movable structuresimultaneously with its horizontal displacement.

The elevating means are advantageously shaped so as to be compatiblewith the roller elements and form lifting ramps.

In a preferred embodiment, the openings consist of orificies defining atleast a first zone designed to allow at least the tops of the rollerelements to project through, a second zone designed to cover the rollerelements, and an intermediate zone which forms, in combination with theroller elements, said lifting ramps. The second zone with openings maybe designed to block the roller elements in said rack openings in orderto lock the position of the rack in relation to the table.

The roller devices may be spherical balls or bi-conical rollers, whilethe intermediate zone with openings would then be essentially ellipticalor triangular in shape and converging toward the second zone. The firstand second zones with openings may have a transverse dimension rangingrespectively from 60 to 95% and from 10 to 45% of the diameter of theroller element.

Preferably the rack is movable in relation to the table supporting theroller elements, which is fixed, said rack being connected to theactuating means.

In this embodiment, the actuating means comprises at least one handlemovable in translation inside a guide block integral with the table andoriented in an essentially perpendicular direction to the horizontaldisplacement of the rack, said rack comprising a guide groove traversedby the handle and angularly offset in relation to the guide block so asto generate horizontal displacement of the rack. These actuating meansmay comprise at least one locking device for attaching the rack to thetable in at least one of its raised or lowered positions.

For the same purpose, the invention concerns a load handling platform ofthe type indicated in the preamble, characterized in that it comprisesat least one roller device as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the present invention will be more apparent from thefollowing description of several embodiments cited by way ofnon-limiting example, with reference to the attached drawings, wherein:

FIG. 1 is a perspective of a roller device according to the invention inthe form of a platform;

FIG. 2 is a partial side view of the device of FIG. 1;

FIG. 3 is a functional schema of the device of FIG. 1;

FIG. 4 is a detailed view of a roller device cooperating with a light onthe device of FIG. 1;

FIG. 5A is a view of a variation similar to FIG. 4 and FIG. 5Billustrates the corresponding roller element.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, roller device 10 according to theinvention is formed like a platform and is designed to equip aconventional platform load handling apparatus (not shown). It ensurestwo functions: static maintenance with friction of heavy loads 1weighing up to about two tons while the load handling device is moving,and dynamic maintenance of these loads 1 without friction while they arebeing transferred in a plane parallel to the platform. In certainapplications, this roller device 10 can be used alone or in combinationwith other equipment.

This roller device 10 comprises a roller supporting structure 20consisting of roller elements 23 surmounted by a load supportingstructure 30 having one plane contact surface S provided with openings32 that allow at least the tops of roller elements 23 to be visible. Inthis exemplary embodiment, as shown schematically in FIG. 3, the loadsupport structure 30 is movable relative to the fixed roller supportstructure 20 between two stable fixed positions: a raised position inwhich it covers roller elements 23, with load 1 in plane contact withsurface S of the load support surface 30, and a lowered position inwhich it uncovers the tops of roller elements 23, with load 1 being incontact at some points with roller elements 23. Obviously, the reverseconfiguration is also possible, that is, the roller support structure 20may be movable in relation to load support structure 30.

Load support structure 30 is associated with actuation means 40 fordisplacing it in horizontal translation Th on a course Ch and withlifting means 50 in order for displacing it in vertical translation Tvon a course Cv simultaneously with its horizontal displacement Th, path.Cv being shorter than path Ch. The originality of roller device 10 ofthe invention resides in the fact that lifting means 50 does not consistof costly, complex supplemental mechanisms, but rather, it is directlyintegrated within load support structure 30 and roller support structure20. The fact that the vertical and horizontal displacements occursimultaneously is due to the moving contact between openings 32 in loadsupport structure 30 and roller elements 23 in the roller supportstructure 20, said openings 32 and said roller elements 23 being shapedspecifically to form a lifting ramp as described below.

In the example shown the roller-support structure 20 consists of a table21 designed for use in the horizontal position, said table 21 beingrectangular and supporting demi-cage pivot joints 22 receiving balls 23to form axial pivots. These balls 23 constitute the roller elements onsaid roller device 10 and are uniformly distributed in the same plane,while the tops of balls 23 fall within a plane parallel to the planecontact surface S of load support structure 30. Table 21 is designed toeither fit in the same place and position as the existing platform on astandard load handling platform or to be superimposed on it.

Load support structure 30 consists of a generally rectangular rack 31superimposed on table 21 having longitudinal edges 31′ bent at a rightangle against edges 21′ of table 21 to form longitudinal guides. Saidrack 31 moves freely along said longitudinal guides in horizontaltranslation Th and in vertical translation Tv. It is associated with anactuation means 40 which is manual in the example shown and consists ofa handle 41 located along an axis that is perpendicular to the surfaceof rack 31 and guided inside a guide block 42 with balls integral withtable 21 and oriented perpendicular to Th. Rack 31 supports a plate 43equipped with a guide groove 44 traversed by handle 41, said grooveextending along guide block 42 between a first extremity locatedopposite said guide block 42 and a second extremity separated from saidguide block 42 by a distance that corresponds to the path Ch followed byrack 31. The actuation means 40 also comprises a locking device 45consisting of a button movable along an axis parallel to handle 41 andprojecting below rack 31 so as to be encased within table 21 and preventaccidental displacement of rack 31. Obviously said actuation means 40might consist of any other equivalent means such as, for example, acylinder, a nut and bolt system, a ball and socket joint, a lever thatis automatically activated when the load handling device approaches themachine tool destined to receive the load, or the like.

Openings 32 in rack 31 consist of generally elliptical orificies 32distributed along the entire surface of rack 31 and located oppositeballs 23. Therefore, there is an equal number of orifices 32 and balls23. They are oriented parallel to the direction of horizontaldisplacement Th of rack 31 and extend for a length that is essentiallyequal to the path Ch of said rack 31. With reference to FIG. 4, eachorifice 32 defines at least a first zone 32 a designed to uncover thetop of a ball 23, a second zone 32 b designed to cover ball 23, and anintermediate zone 32 c designed to form, together with ball 23, liftingmeans 50. The first zone 32 a is formed of a semi-circle with a diameterranging from, for example, 60 to 95% of the diameter of balls 23 so asto allow the tops of balls 23 to project beyond the surface of rack 31.The second zone 32 b is formed of a nearly complete circle with asmaller diameter than that of first zone 32 a and ranging for examplefrom 10 to 45% of the diameter of balls 23 in order to cover and blockthem. This second zone 32 b performs a complementary locking function,as the top of ball 23 remains trapped inside this zone. This securitysystem blocks rack 31 in the upper position, while maneuvering handle 41in the opposite direction causes it to return to the lower position.Intermediate zone 32 c is generally elliptical and extends from firstzone 32 a to second zone 32 b as it narrows. The two edges of thisintermediate zone 32 c are therefore slightly curved and converge so asto form, together with spherically shaped ball 23, a lifting ramp. Theangle of inclination of both this lifting ramp and guide groove 44 aredesigned to reduce the force that must be applied to maneuver handle 41,which is approximately 20 kg to lift a one ton load.

The shape of orifices 32 and roller elements 23 may, of course, vary asa function of the weight of load 1. With heavier loads, for example, asshown in FIGS. 5A and 5B, bi-conical rollers 24 and generally triangularorifices 33 are used. Rollers 24 are integral with axles guided insidesupports attached to table 21. These bi-conical rollers 24 have apartially spherical central portion and truncated sides with a shapethat is compatible with the V-shaped edges of intermediate zone 33 c oforifices 33. First and second zones 33 a and 33 b remain the same, whilezone 33 a may be semi-hexagonal in shape.

It is readily apparent that the concept of roller device 10 inaccordance with the invention is based on simple kinematics, making itinexpensive to purchase and maintain, less cumbersome, and more durable.

The roller device 10 as described can be sold as a platform to retrofitload-handling apparatuses already in use, or integrated into newequipment. This is the reason that the invention also applies toload-handling apparatuses (not shown) equipped with such a roller device10.

The present invention is not limited to the exemplary embodimentsdescribed, but extends to any modification and variation obvious to aperson skilled in the art while remaining within the scope of protectiondefined by the attached claims.

1. A roller device (10) for displacing a load (1) in an essentiallyhorizontal plane comprising at least one essentially horizontal table(21) to which roller elements (23, 24) are attached, at least one rack(31) covering said table (21) equipped with openings (32, 33) locatedopposite said roller elements (23, 24), said rack (31) defining a planecontact surface (S) for supporting said load when the load is static andsaid roller elements (23, 24) being located in a plane essentiallyparallel to said surface (S) and able to support said load when the loadis moving, an actuating means (40) being associated with at least one ofthe rack (31) and the table (21) to be movable relative to another ofthe rack (31) and the table (21) between at least a lower position andan upper position wherein the load is supported either by the rack (31)or by the table (21), said actuating means (40) displaces one of therack (31) and the table (21) at least in a horizontal translation (Th),and said openings (32, 33) of the rack (31) have a shape compatible witha shape of the roller element (23, 24) to form lifting ramps so as tocause the one of the rack (31) and the table (21) to move in verticaldisplacement (Tv) simultaneously with the horizontal displacement (Th).2. A load handling platform comprising at least one roller device (10)for displacing a load (1) in a generally horizontal plane comprising atleast one generally horizontal table (21) to which roller elements(23,24) are attached, at least one rack (31) covering said table (21)having openings (32,33) located opposite said roller elements (23,24),said rack (31) defining a plane contact surface (S) capable ofsupporting said load when the load is static and said roller elements(23, 24) being located in a second plane generally parallel to saidsurface (S) and capable of supporting said load when moving, anactuating means (40) associated with at least one of the rack (31) andthe table (21) to be movable in relation to another of the rack (31) andthe table (21) between at least a lower position and an upper position,the load is supported by either the rack (31) or by the table (21),actuating means (40) displaces the rack (31) and the table (21) at leastin a horizontal translation (Th), wherein said openings (32, 33) on rack(31) have a shape compatible with the shape of the roller elements (23)to form lifting ramps so as to generate a vertical displacement (Tv) bythe rack (31) or the table (21) simultaneous with the horizontaldisplacement (Th).
 3. The load handling platform according to claim 2,wherein the openings (32, 33) consist of orifices defining at least afirst zone (32 a, 33 a) that allows at least tops of the roller elements(23, 24) to project, a second zone (32 b, 33 b) which covers the rollerelements (23, 24), and an intermediate zone (32 c, 33 c) which forms, incombination with the roller elements (23, 24), said lifting ramps.
 4. Aroller device (10) for displacing a load (1) in substantially ahorizontal plane comprising at least one substantially horizontal table(21) to which roller elements (23, 24) are attached, at least one rack(31) covering said table (21) equipped with openings (32, 33) locatedopposite said roller elements (23, 24), said rack (31) defining a planecontact surface (S) for supporting said load when the load is static andsaid roller elements (23, 24) being located In a plane substantiallyparallel to said surface (S) and able to support said load when the loadis moving, an actuating mechanism (40) being associated with at leastone of the rack (31) and the table (21) to be movable relative toanother of the rack (31) and the table (21) between at least a lowerposition and an upper position: wherein the load is supported either bythe rack (31) or by the table (21), said actuating mechanism (40)displaces one of the rack (31) and the table (21) at least in ahorizontal translation (Th), and said openings (32, 33) of the rack (31)have a shape compatible with a shape of the roller element (23, 24) toform lifting ramps so as to cause the one of the rack (31) and the table(21) to move in vertical displacement (Tv) simultaneously with thehorizontal displacement (Th); and the openings (32, 33) consist oforifices defining at least a first zone (32 a, 33 a) which allows atleast tops of the roller elements (23, 24) to project, a second zone (32b, 33 b) for covering the roller elements (23, 24) and an intermediatezone (32 c, 33 c) which together with the roller elements (23, 24) formslifting ramps.
 5. The device according to claim 4, wherein the secondzone (32 b, 33 b) with the openings is designed to block the rollerelements (23, 24) in said openings (32, 33) on the rack (31) In order tolook in a position of said rack (31) relative to said table (21).
 6. Thedevice according to claim 5, wherein the roller elements are sphericalballs (23) and the intermediate zone (32 c) with the openings (32) isgenerally elliptical in shape, converging toward the second zone (32 b).7. The device according to claims 6, wherein the first and second zones(32 a, 33 a, 32 b, 33 b) of the openings (32, 33) have transversedimensions ranging respectively from 60 to 95% and from 10 to 45% of thediameter of the roller elements (23, 24).
 8. The device according toclaim 5, wherein the roller elements are bi-conical rollers (24) and theIntermediate zone (33 c) with the openings (33) is generally triangularin shape, converging toward the second zone (33 b).
 9. The deviceaccording to claim 5, wherein the rack (31) is movable and associatedwith an actuation means (40) and the table (21) supporting the rollerelements (23, 24) is fixed.
 10. The device according to claim 9, whereinthe actuating mechanism (40) comprises at least one handle (41) movingIn translation within a guide block (42) integral with the table (21)and oriented In an essentially perpendicular direction to the directionof horizontal displacement (Th) by the rack (31), said rack (31)comprising a guide groove (44) traversed by said handle (41) andangularly offset in relation to the guide block (42) so as to generatehorizontal displacement of the rack (31).
 11. The device according toclaim 10, wherein the actuating mechanism (40) comprises at least onelocking element (45) for connecting the rack (31) to the table (21) inat least one raised or lowered position.